The present invention relates generally to the field of electronic devices, and more particularly to replacing physical controls with virtual controls of the electronic devices utilizing low capacitive sensing.
Capacitive sensing is a technology, based on capacitive coupling (i.e., transfer of energy by displacement of a current induced by an electric field), that detects and measures conductivity associated with conductive materials or has a dielectric (i.e., property of an electrical insulating material) that is different from air. Capacitive sensing systems include: mutual capacitance, where an object (e.g., finger, conductive stylus) alters mutual coupling between rows and columns of electrodes that are scanned sequentially; and self or absolute capacitance, where the object loads the sensor or increases the parasitic capacitance to ground. In basic capacitive sensing technology, only one side of an insulator is coated with conductive material. A small voltage is applied to the conductive layer, resulting in a uniform electrostatic field. When a conductor touches the uncoated surface, a capacitor dynamically forms. Due to the sheet resistance of the surface, each corner is measured to have a different effective capacitance. The sensor's controller determines the location of the touch indirectly from the change in the capacitance as measured from the four corners of the panel: the larger the change in capacitance, the closer the touch is to that corner. For example, a person touches a touch a lamp that is touch sensitive. The lamp alone has a fixed capacitance, (i.e., a circuit connected to the lamp would utilize a specified number of electrons to charge or fill the lamp with electrons). The person also includes a fixed capacitance, and when the person interacts with the lamp, the capacitance of the person add to the capacitance of the lamp. The circuit connected to the lamp detects the change in capacitance and registers the interaction.
With respect to a touchscreen, capacitive touch sensors create an electric field above the glass of the touchscreen that are associated with an image map denoting a sensing region of the touchscreen. Within the touchscreen, sensing circuitry detects minute changes in the electric field (i.e., changes in the touchscreen electrode's capacitance values) within the sensing region. Analysis and filtering of the changes in the image map result in an extraction of a signal from noise. Algorithms are applied to the signal to identify objects of interest that interact and/or are near the surface of the touchscreen. The capacitive touch sensors also detect motion which is tracked with respect to the touchscreen and the image map.